Tools of the type generally mentioned above are used for chip removing or cutting machining of work pieces of metal or the like materials, e.g. composites. A usual machining method is turning, in the form of grooving or parting operations, during which the cutting insert is fed in radially into a rotating work piece to form a circumferential groove in the same. In grooving, the cutting insert is inserted to a moderate depth in the work piece, while parting requires that the cutting insert is inserted to the vicinity of the center axis of the work piece. Tools of the kind in question may also be mounted in rotatable milling cutters having the purpose of providing straight slots in, for instance, a flat surface of a work piece. In both cases, however, it is required that the blade serving as a holder for the cutting insert has a thickness that is less than the width of the front, active main cutting edge of the cutting insert, which determines the width of the groove, because otherwise the blade would not clear from the generated, flat surfaces that delimit the groove. As a consequence of their practical application, the tools are commonly denominated “parting tools”.
In this connection, it should be mentioned that the replaceable cutting insert is usually manufactured from cemented carbide or another hard material having large resistance to wear, while the holding blade is manufactured from steel of a suitable quality. The last-mentioned material has—contrary to the hard material of the cutting insert—a certain inherent elasticity, which can be utilized to clamp the cutting insert in the seat of the blade.
Since large amounts of heat are generated during the machining, usually an efficient cooling of the cutting insert and its immediate environment is required. Therefore, traditionally, the cutting insert is cooled from above (overcooling) as well as from below (undercooling).
A tool of the type initially mentioned is disclosed by JP 7-227702. In one of several alternative embodiments, the cutting insert is cooled by overcooling as well as undercooling. In order to provide for overcooling, a flushing channel is arranged in the clamping finger that has the purpose of fixing the cutting insert in the appurtenant seat. The cutting insert includes a front rake surface, as well as a rear application surface, against which the clamping finger abuts. At the front nose of the clamping finger, the cutting insert is formed with a shoulder having the shape of a countersunk surface, which is located immediately behind the rear boundary line of the rake surface and extends essentially vertically downward toward a front boundary line for the application surface. The clamping finger is delimited between an upper side and an under side, which converge toward the nose. The upper side of the clamping finger and the rake surface of the cutting insert are slightly concave (as viewed from the side), so that they together—in the mounted state of the cutting insert—form a concave sink along which the removed, but not yet released, chip can slide until the same has cooled and been formed into a solitary fragment.
A disadvantage of the tool known by JP 7-227702 is that the mouth of the flushing channel is spaced apart from the nose of the clamping finger at the same time the chip does not meet any chip-forming obstacle at all on its way along the upper side of the clamping finger. This means that the cooling medium jet immediately impinges on the chip (and per se cools the same) without efficiently reaching up to the rake surface of the cutting insert. This means that the rake surface and the front main cutting edge get an inferior overcooling.